1. Field of the Invention
The present invention relates to systems and method for treating osteonecrosis that effects load bearing musculoskeletal structures.
2. Prior Art Statement
Osteonecrosis, in the form of avascular necrosis, aseptic necrosis or subchondral avascular necrosis can be caused by either disease or trauma. The most common bones effected by such a condition include the femoral head, the knee, the humeral head and the small bones of the wrist and foot. Avascular necrosis occurs when vascular fibrous tissue is deposited in an area of damaged bone. During this period, damaged, unviable bone is absorbed into the body, while new immature woven bone is deposited. As old bone is absorbed and replaced with new immature bone, the structural integrity of the bone decreases. When stressed under a load, the immature bone can mechanically fail.
When the femoral head is involved, bone failure typically happens when a section of the femoral head collapses. As a section of the femoral head collapses, the articular cartilage above the area of collapse is unsupported or under supported. The antero-lateral margin of the acetabulum (hip socket) creates an indentation in the unsupported articular cartilage, which compacts the weakened underlying subchondral bone. After structural failure of the subchondral bone, many patients require total hip replacement surgery in order to eliminate pain from the hip and to regain full mobility of the hip.
The prevalence of avascular necrosis is unknown. However, it has been estimated that between ten thousand and twenty thousand new cases develop every year in the United States.
To treat avascular necrosis in the hip, it has been attempted, in the prior art, to reinforce the weakened femoral head with bone grafts before a total hip replacement becomes necessary. The bone used in a bone graft is typically harvested from the pelvis, fibula or tibia. The harvested bone is then introduced into the femoral head through a hole that is drilled into the femoral head. Although the use of bone grafts is effective, it is not without disadvantages. The use of bone grafts causes damage in the area that the bone is harvested. The large hole drilled into the femoral head, causes weakness in the femoral neck. Long post-operative periods of rehabilitation are required in order for a patient to heal. Lastly, treatment of avascular necrosis with bone grafts requires a very complex and time consuming operating procedure.
A need therefore exists for a system and method of treating avascular necrosis in a manner that does not require bone grafts, is less detrimental to the remaining healthy sections of the effected bone and requires a simpler operating procedure. This need is met by the present invention as described and claimed below.
The present invention is a system and method for treating a necrotic section of bone. Utilizing the present invention, at least one channel is drilled into a bone from a common point. Each channel has a distal end that terminates in the subchondral bone proximate the necrotic section of bone. A volume of bone growth inducing compound is introduced into each channel. The volume of bone growth inducing compound is biased toward the distal end of each channel with a screw, wherein the bone growth inducing compound permeates the necrotic section of bone. Once the bone growth inducing compound has permeated the necrotic section of bone, the bone growth inducing compound promotes rapid bone growth and thus healing of the necrotic section of bone. Furthermore, the advancement of the screw into the channel provides instant structural support to the necrotic section of bone.